<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"> 
<title>css3基础</title> 
<style> 
div
{
	border:2px solid #a1a1a1;
	padding:10px 40px; 
	background:#dddddd;
	width:300px;
	border-radius:25px;
}
</style>
</head>
<body>

<div>border-radius 属性允许您为元素添加圆角边框！ </div>

</body>
</html>